Quantifying environmental water needs – eWater Ecological Tools

eWater Road Show 21 Feb – Part 5 of 5

Dr Nick MarsheWater

Using eWater tools to approach the problem

1) Identifying the problem – who are the stakeholders and how will they be affected?

• Concept

2) Quantifying the environmental benefit of a given watering scenario

• Eco Modeller

3) Determining how much additional water may be required

• Eflow Predictor

Wivenhoe Dam

Wivenhoe Dam – after heavy rain Jan 2011

Eco Modeller: Blackfish in the South Esk River

River Blackfish habitat requirements

• Magnitude: How much water

do they need?

• Duration: how long do they

need it for?

• Timing: When do they need it?

• Frequency: How long between

successful events?

• Rate of Change: do rapid

rates of flow change influence

success?

Blackfish in Esk River

Natural Max extraction Modified

Flow (ML/D) 962 451 522

Water extracted 53% 45 %

Reduction in blackfish habitat score 38% 16%

Example 2: Consider River Red Gum vegetation communities in Barmah forest

River Red Gum habitat availabilityEco Modeller results

asset Predevelopment Current

River Red Gum Forest Adult 27% 14%

River Red Gum Forest Recruitment 47% 23%

River Red Gum Woodland Adult 11% 6%

River Red Gum Woodland Recruitment 39% 19%

Two modelled scenarios (110 years 1896-2006)

• Predevelopment = all consumptive use turned off for entire period

• Current = all current consumptive use turned on for entire period

• Score = Mean annual habitat score (% of ideal)

45 % to 50% decrease in the mean annual habitat score from predevelopment to current scenario

Volume of augmented flow

Commence to fill trigger

ML/d

days

Consider adding more water –eFlow Predictor

Create some new flow scenarios by increasing the flow at specific parts

of the hydrograph to mimic the natural frequency of these small

events

Option Additional Water Cost (% of current)

18,300ML/d 60 days return to pre-development frequency 4.4%

18,300ML/d 30 days return to pre-development frequency 2.6%

18,300ML/d 30 days max 1 in every 2 years 1.0%

0

10

20

30

40

50

60

70

60 days nat freq 30 days nat freq 30 days max 1 in 2 years freq

Incr

ease

in m

ean

annu

al h

abit

at sc

ore

Scenarios

RRGF Adult RRGF Recruitment RRGW Adult RRGW Recruitment

What impact do these flow changes have on River Red Gum?

4.4% flow increase

2.6% flow increase

1.0% flow increase

Hattah Lakes

RAMSAR wetland~ 20 lakesPart of 48,000ha Hattah-Kulkyne National Park

Credit to Stuart Little (MDBA) and Bernard McCarthy (MDFRC)

Murray Icon site assets

Fish1. Golden perch2. Silver perch 3. Macquarie perch 4. Australian smelt5. Bony herring6. Carp gudgeons7. Southern pygmy perch,

Hardyheads8. Galaxias rostratus9. Freshwater catfish 10. Australian smelt11. Bony herring12. Flathead gudgeons13. Murray Cod14. Trout cod15. River blackfish16. Two-spined blackfish17. Crimson-spotted rainbow fish18. Carp gudgeons

Vegetation1. River red gum forest2. River red gum woodland3. Black box woodland4. Lignum shrubland

Rats Tail Couch grassland/Edge

5. Cumbungi (Typha) rushlands

6. Phragmites australis

rushlands

7. Spiny mudgrass (Moira grass)

grasslands

8. Giant rush rushlands

Birds1. Colonial nesting waterbirds -

includes ibis, egrets herons

and spoonbills

2. Waterfowl and grebes -

includes the flood dependent

species such as grey teal,

pinkeared duck, freckled

duck, Australasian shoveler,

great-crested grebe, hoary-

headed grebe

Change from natural to current scenariosDecrease in Mean annual score

Increase in the number of poor years

Decrease in the number of good years

Time between good years

Flow data 43% 180% 69% 83%FishFish in main channel 4% 30% 18% 0%Fish in Hattah Lakes 36% 167% 59% 0%Silver Perch main channel 36% 156% 73% 83%Silver Perch connection to lakes 75% 225% 93% 658%Golden Perch main channel 41% 201% 79% 183%Golden Perch connection to lakes 69% 208% 90% 600%BirdsColonial Nesting Water Birds Breeding

55% 160% 59% 83%Waterfowl and Grebes breeding 53% 163% 62% 83%Water Birds Feeding 42% 163% 66% 120%Floodplain VegetationRiver Red Gum Forest Adult 66% 139% 76% 74%River Red Gum Forest Recruitment 68% 139% 73% 125%River Red Gum Woodland Adult 72% 174% 83% 280%River Red gum Woodland Recruitment

63% 153% 66% 83%Black Box Woodland Adult 68% 208% 62% 83%Black Box Woodland Recruitment 62% 208% 66% 83%Lignum shrubland Adult 71% 208% 73% 208%Lignum shrubland Recruitment 66% 208% 69% 183%Rats Tail couch Adult 68% 208% 69% 94%Rats Tail Couch Recruitment 66% 208% 62% 83%Wetland VegetationCumbungi Adult 38% 290% 100% 736%Cumbungi Recruitment 55% 249% 100% 1200%Phragmites Australia Rushlands Adult 45% 204% 8% 400%Phragmites Australia Rushlands Recruitment

40% 201% 1% 650%Spiny Mudgrass (Moira Grass) grasslands Adult

51% 286% 88% 1150%Spiny Mudgrass (Moira Grass) grasslands Recruitment 81% 297% 100% 388%Giant rush Rushlands Adult 75% 238% 56% 175%Giant rush Rushlands Recruitment 80% 279% 83% 229%Ribbonweed Adult 49% 300% -3% 600%Ribbonweed Recruitment 34% 0% 66% 500%

Average habitat halved or worse

3 times as many high stress years

Hardly any recruitment opportunities

Good years halved or worse

Good years = > 75th percentile of natural

-20%

0%

20%

40%

60%

80%

100%

120%Decrease in good years

Fish Birds Floodplain veg Wetland veg

Ecological tools to help water management

• Concept

Gaining consensus in system understanding and problem definition

• eFlow Predictor

Predicting the how much environmental water is required

• Eco Modeller

Defining ecological water requirements and quantifying the impact of alternative flow regimes

www.ewater.com.au

www.toolkit.net.au